BP has drawn up contingency plans to tackle an oil spill off Shetland, twice the size of its Deepwater Horizon disaster in the Gulf of Mexico.The oil giant revealed its "worst-case scenario" Oil Pollution Emergency Plan in a submission to the UK government.The company is seeking approval to start drilling a new exploratory well 80 miles north west of the islands early next year.WWF Scotland claimed BP's plans would not prevent a major impact on wildlife.BP has been exploring the deep waters west off Shetland since the 1970s and producing oil from the area for more than 15 years.Its latest plan is to drill a new well, known as the North Uist, in a depth of nearly 1,300m of water.BP has outlined a potential situation involving a leak of 75,000 barrels a day for 140 days - a total of 10.5 million barrels of oil.It said it had incorporated the lessons learnt from the Deepwater Horizon incident into the overall planning for the well.Dr Richard Dixon, from WWF Scotland, told BBC Scotland the risks involved in drilling were too greatHe said: "This is a worst case scenario, but it is a realistic scenario. So this could happen."If things went wrong in the same way they went wrong in the Deepwater Horizon disaster, and the measures that BP tried to put in place didn't work very well, we could have 140 days worth of very significant oil spill."This could be a 100-times worse than the Braer disaster."The disaster, in 1993, saw a tanker run aground off the coast of Shetland resulting in an oil spill of 85,000 tonnes.